The oil and gas industry is categorized into two types of activities: Upstream and Downstream. The Upstream is composed of Exploration and Production (E&P), while Downstream deals with refining and processing of crude oil and gas products, their distribution and marketing.

In the environmental sector, the various phases of the Upstream industry are of interest due to the lessons learned by countries where there are oil and gas developments. Environmental impacts from the activities arising from the exploration phase until the project is decommissioning are well documented.

Each stage can bring about potential negative effects on the environment, whether on the marine ecosystem, coastal areas and on the land. The activities at each stage may produce potential contaminants, which will result in impacts that may be different in offshore from onshore due to the different kinds of receptors within these types of environment.

For both offshore and onshore development the following potential environmental issues are given emphasis:
- Air emission (air quality)
- Noise generation
- Waste water discharges
- Solid and liquid wastes
- Spills
- Environmental Issues

In addition to the ecological impacts of oil and gas activities, socio-economic impacts may arise, should spills of oil, toxic and hazardous chemicals occur. If not adequately addressed, the impacts of decommissioning may produce long term effects on the marine ecosystems. Toxic and hazardous wastes and materials, if left within the offshore installation and abandoned structures, may pose a danger to ships and fishermen. The CNPA is working actively in close cooperation with the concerned ministries, institutions and international organizations in the area of environmental protection related to Petroleum Operations. Environmental Impact Assessment (EIA) is required for oil and gas operations.

Legal Background in Cambodia In its regulatory role, the Cambodian National Petroleum Authority is mandated to assess and monitor environmental impacts of oil and gas projects. With the Environmental Law and Sub-Decrees, the Royal Kingdom of Cambodia has the following legal framework, that can be found directly on the official website of the Ministry, mainly in Khmer language: Law on Environmental Protection and Natural Resource Management

- Sub-Decree on EIA
- Sub-Decree on Water Pollution Control
- Sub-Decree on Solid Waste Management
- Sub-Decree on Control of Air Pollution and Noise Disturbance
- Declaration on the Management and Elimination of Forest Anarchy

Health and Safety

The documentation required by a Contract Operator to conduct petroleum activities should include a Safety Management Plan, Emergency Response Plan and Oil Spill Contingency Plan.

The Safety Management Plan The Safety Management Plan (SMP) should detail a system for the management of all hazards and risks to health and safety - it is not limited to potential accidents. The SMP should provide for the establishment and maintenance of a "permit to work" system that controls and coordinates safe performance of work activities,, including welding, other hot work, physical isolation, electrical work etc. The SMP should specify the equipment required, that relates to or may affect the safety. The SMP should also describe how the operator ensures the securing, supplying and monitoring of therapeutic drugs, and the preventing of use of other controlled substances and intoxicants.

The Emergency Response Plan

The Emergency Response Plan (ERP) should detail an analysis of evacuation, escape and rescue, and a detailed description of a fire and explosion risk analysis. The ERP should provide for adequate systems for emergency communication, to handle any likely emergency, as well as the operational requirements to be protected and capable of operating to the extent specified by the Formal Safety Assessment. This includes: Evacuation and escape routes

Alternates routes in case the primary routes are not available Procedures for responding to emergencies

Means and equipment for evacuation, escape and rescue .Amenities and communication facilities to be provided in a temporary refuge .Life saving equipment's .Similarly, fire and explosion risks detail the type of fire and explosions that may occur and take into account a range of possible: Measures for detecting fires and explosions measures for eliminating or reducing fires and explosions .Automatic and manual systems for detection, control and extinguishment

Means of isolating and safety storing hazardous substances

Oil Spill Contingency Plan

The primary focus of oil spill management is spill prevention. The secondary focus is procedures for oil spill response through the development and maintenance of an Oil Spill Contingency Plan (OSCP). The OSCP is a project-specific plan and an important part of an application to carry out offshore petroleum activities. An OSCP is an operational document for an emergency situation; it should include the following components: Planning and strategy development (priorities, structure of the response, EIA, responsibilities)